The present invention related to a sealing device for a rolling bearing for isolating the bearing from outside to prevent water, scales from entering the interior of the bearing and rolling element lubricant e.g., grease or oil air lubricant from leaking out of the bearing.
A tern "seal holder portion" means a portion on which a seal body is mounted, which formed within a seal holder being separately provided and closely engaged with the end face of an outer ring or a portion on which the seal body is mounted, which is directly formed on the end of the outer ring without mounting of a seal holder separately provided.
FIGS. 20A and 20B shows a sealing device 100 for a four-raw tapered roller bearing used mainly for a steel rolling mill. A sealing device of the type in which a sealing member 700 is fit into a seal holder portion 602 of a ring-like seal holder 600 is typically known.
Another sealing device 101 not provided with a separate seal holder as shown in FIG. 21 is also known. In the sealing device 101, a sealing member 700 is fit into the seal holder portion 602 directly formed on the outer ring.
In the sealing device 100 of FIGS. 20A and 20B, to seal the bearing, the side wall of the seal holder 600 is brought into close contact with an outer ring 200, and a lip portion 701 of the sealing member 700 is made to slidably contact with the outer peripheral surface 301 of an inner ring 300. The same thing is correspondingly applied to the sealing device of FIG. 21.
Reference is made to FIG. 20A. The bearing includes a cage type holder 500. The bottom 501 of the cage type holder 500 (so called as a retainer) is positioned off the bearing width C. In other words, the bottom 501 of the cage type holder 500 is protruded from the side edge of the outer ring 200.
In order to avoid the interference among the cage type holder 500, the sealing member 700 and the seal holder 600, it is necessary to increase the width of the seal holder 600 and to locate the soaling member 700 close to outside. Such a structural requirement limits the space or a bearing unit, and hence of necessity reduces the load capacity. To cope with this, a sealing device as shown in FIG. 20B is proposed.
In the sealing device 100 of FIG. 20B, the sealing member 700 includes a recessed portion 702. The space 703 defined by the recessed portion 702 may receive the bottom 501 of the cage type holder 500. This structural feature brings about advantages: no interference of the cage type holder 500 with the sealing member 700, the width reduction of the seal holder 600, and the increase of the load capacity of the bearing.
The four-raw tapered roller bearing must be attached to and detached from the chock in a state that it is assembled and sealed. Because of this, the necessity is to use a bearing suspending tool 800 (FIG. 19), used for-only the purpose of bearing suspension.
In the sealing device of FIG. 20B, the recessed portion 702 is horizontally extended from a flange portion 704 sandwiched between a groove 601 of the seal holder 600 and the end face of the outer ring. The structure ensues the increase of the inside diameter of the seal holder 600, and the height of the sealing member 700 when viewed in cross section. For this reason, the FIG. 20B sealing device rejects the use of the bearing suspending tool 800 when an assembly of the sealing device and the bearing is attached to the chock through the bearing suspending tool.